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Item The late Holocene vegetational and climate history of Western Hawkes Bay : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Quaternary Science at Massey University(Massey University, 1998) Hannan, Colleen ThereseSediments from (a) a flush, two peat mires and two ponds from a 94 km transect along the Mohaka Fault trace (a northern extension of the Wellington Fault) set in the eastern foothills of the Ruahine Range, in western Hawkes Bay, New Zealand, and (b) from a lake at Te Pohue in northwestern Hawkes Bay, are analysed for their pollen and charcoal records to reconstruct the late Holocene vegetational and climatic history of the region. Western Hawkes Bay lies westward of an obliquely converging plate boundary, the Hikurangi Trough. This oblique convergence has resulted in tectonic strain being partitioned into domains of extension, contraction and strike-slip across Hawkes Bay. Within the study area, strain has resulted dominantly in primary tectonic landforms such as fault scarps and fault lines, and secondary tectonic landforms such as tilted and folded surfaces. Features of movement along the Mohaka Fault in the geomorphology include right-laterally offset streams, ridges with distinctive linear troughs along the line of the fault and the formation of triangular spurs. The region generally has a warm, dry climate, and suffers from drought periodically, with the drought often being broken by heavy rains in the autumn. These rains may be of cyclonic proportion. Due to both seismic and co-seismic activity in the region, the landscape is both uplifted and broken, and continually subject to mass movement; localised topoclimates are also common. This study determines how the western Hawkes Bay vegetational cover and its composition have changed in response to late Holocene climate changes through analysis of sediment cores. Also addressed is the extent to which tectonism, volcanicity, fire, major storm events and human activity have left a local overprint on the regional vegetational pattern. Climatically the region may be divided into three sectors: a dry central sector, (Big Hill site); flanked by moister southern and northern sectors. The regional vegetation in the southern sector was dominated by a Nothofagus- mixed podocarp forest in the Kashmir region from c. 800 yrs BP. up to when the site was affected by fire in 1888. In the Hinerua region, 14 kms farther north, Nothofagus fusca with a minor Dacrydium cupressinum-dominated/ mixed podocarp forest, was established by c. 2790 yrs BP. The regional vegetation of the central sector from c. 3700 to 3000 yrs BP. was predominantly a Prumnopitys taxifolia/mixed podocarp forest. There was also a notable Nothofagus component. There is a c 1900 year hiatus in the vegetation record between c. 3000 and 1150 yrs BP when no sediment accumulated at the Big Hill site. The regional forest of the central sector at c. 1150 yrs BP. was still a predominantly Prumnopitys taxifolia-dominated/mixed podocarp forest. However, Nothofagus was less important in this latter forest. At Willowford, 18 kilometres north of Big Hill, the same Prumnopitys taxifolia -dominated/mixed podocarp forest was evident at about 500 yrs BP. At Hawkstone, 10 kms north of Willowford, a Nothofagus/ P. taxifolia-dominated mixed podocarp forest was established by 6500 yrs BP. About 3400 yrs BP Dacrydium cupressinum became the dominant podocarp, thus placing the Hawkstone region within the northern climatic sector from this date, up to the present. The regional vegetation of the northern sector from 1850 yrs BP. until European land clearance in the late 19th century at Te Pohue, was a Dacrydium cupressinum -dominated/mixed podocarp assemblage with a notable Prumnopitys taxifolia component. Several erosional events have been identified in the stratigraphy of the sites. By estimating the age of these events by sediment accumulation rates, some of these events have been tentatively linked to Grant's (1985) hypothesis of periodic climate-forced erosional events having partially destroyed the forest cover in the western Hawkes Bay region. Using radiocarbon dates from this study, often in conjunction with sediment accumulation rates, it has been possible to identify some erosional events as earthquake generated by linking these events to other known and radiocarbon dated movements along the Mohaka Fault trace in western Hawkes Bay. Volcanicity has been identified as a factor influencing forest cover in the northern pari of western Hawkes Bay. At Hawkstone, microscopic charcoal has been identifed at several levels throughout the 6500 year pollen record of the site. However, the sediment accumulation rate was too low to determine the exact nature of the disturbance, and the forest quickly recovered in each case. Although a 0.20 m layer of reworked lapilli from the Waimihia eruption (3280 ± 20 yrs BP.) was recorded at the site, no fire or disturbance to the vegetation was recorded. However, above the Taupo Tephra (1850 ± 10 yrs BP.) fire is continually recorded at the site. As a result the regional forest did not return. Primary ignimbrite from the Taupo eruption forms the base of the Te Pohue site. The regional forest was destroyed by fire in conjunction with this event. A similar forest to before the event, was re-established within c. 230 years. Polynesian deforestation is identified by the advent of high frequencies of Pteridium exculentum and microscopic charcoal in the pollen record in the Willowford region c. 480 ± 170 yrs BP., and in the Big Hill region c. 435 ° 140 yrs BP.; and are coincident with the decline of indigenous forests in each case. European settlement, commencing in the mid-nineteenth century at Te Pohue and about 1880 AD. at Hinerua, is identified by the decline of indigenous forests in these areas, coincident with the appearance of exotic pollen types such as Pinus. Taraxacum and pasture grasses.Item Palaeoecology by palynology : a palaeoecological study of the vegetation of the Tongariro Volcanic Centre, New Zealand, immediately prior to the c. 232 AD Taupo eruption : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Biology at Massey University(Massey University, 2001) Banks, Natalie JaneThe usual source of pollen for analysis has been from within deposits of peat from lakes, bogs and mires. Soils have not generally been considered a potentially useful pollen source. Under some circumstances, however, (such as volcanic eruptions) a soil may be buried so rapidly that the pollen it contains will be more or less completely preserved in the resulting palaeosol. Studies of such volcanically buried palaeosol pollen have been made overseas. The last eruption from the Taupo Volcanic Centre occurred approximately 1800 years ago. The culminating phase of the eruption ejected ca 30 cubic kilometres of ignimbrite as a very hot and fluid pyroclastic flow which covered an area with a radius of 70-90 km centred on Lake Taupo. This deposit is known as the Taupo Tephra. The purpose of the present investigation was to examine peats and palaeosols directly beneath the Taupo Tephra from a variety of sites within the Tongariro area and to analyse any pollen preserved. Samples were taken from a total of 42 sites at various altitudes and distances from the eruptive source, and pollen extracted. Each sample taken, therefore, was from a buried soil or peat directly below the Taupo Tephra. The pollen contained within these samples and contains pollen deposited immediately prior to the eruption. An initial qualitative investigation indicated that the ignimbrite acts as an effective filter in preventing any contemporary pollen and spores from percolating through into underlying layers. The preservation of pollen was reasonably good at most sites allowing some conclusions to be drawn as to the structure and composition of the pre-eruption forests of the Tongariro area. Beech forest was widespread throughout, especially at higher altitudes, although mixed conifer associations were also evident, particularly in the west. At those sites where pollen preservation was poor, some alternative conclusions can be drawn about preservation environments within palaeosols. The pH value is particularly important, and pollen and spores are not well preserved when the soil pH value is in excess of 6.0. The possibility of differential preservation within the New Zealand flora is also examined.Item Quaternary vegetational, environmental and climatic history of the lower Taieri Plain, East Otago, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Quaternary Science at Massey University(Massey University, 2000) O'Brien, Regan WilliamThis project presents the palynology of the 154m Waipori 99-1 long core taken from the Lower Taieri Plain, east Otago, New Zealand. The current vegetation and climate are reviewed along with the geological and geomorphological setting of the Taieri Basin. Reviews are given on the history of New Zealand's vegetation since the Late Cretaceous and on the late Pleistocene and Holocene vegetation and climate of southern New Zealand. The field and lab techniques used in the course of this project are detailed. The Waipori 99-1 long core contained a number of extensive glacial aggradational gravel sequences. These are separated in places by interbedded fine sediments which were found, for the most part, to have been deposited during warm climate periods. Subsidence within the basin has determined which sediments survive in the record. Periodic subsidence and fluvial erosion have resulted in a discontinuous sedimentary sequence. Polliniferous sediments were found only above -103m. Pollen analysis suggests that the sediments may date back as far as the mid Quaternary. Dating on the core poorly constrains sediments which pre-date the Holocene. The pollen evidence presented in this project is used to create a number of possible chronological lines along which to interpret environmental information derived from the core. No particular line is fully endorsed by the project however. As many as four, and possibly five, warm climate pollen assemblages are recognised. Pollen analysis suggests that during these warm periods, podocarp-broadleaf forests occupied the basin. Prumnopitys taxifolia was the most consistently common podocarp in the region. Fuscospora beeches appear to have once been more common in the area in contrast to the present day. Dacrydium cupressinum was apparently absent from the area during the mid to late Quaternary, expanding into the basin only in the mid Holocene. The Holocene vegetational, climatic and environmental record is in agreement with others published from southern New Zealand.Item The palynology of two Whangarei craters, Northland, New Zealand : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Geography at Massey University, New Zealand(Massey University, 2013) Gates, Shirley MayWhangarei lies within the Puhipuhi-Whangarei Volcanic Field, one of two fields located in Northland. The purpose of this project was to use a palynological study to provide information on the minimum ages of the young Whangarei cones, their vegetation history, and the approximate date of human arrival. Wetlands in the craters of the Maungatapere and Rawhitiroa basaltic cones were selected for this study since they both occupy discrete areas which only collect sediment from within their respective cones. A single peat core from each wetland was processed for fossil pollen and radiocarbon dating. Radiocarbon dating was performed by the University of Waikato, providing minimum ages for the volcanoes. The date for the base of the Maungatapere core was 10530 ± 136 cal. yr BP, and an age of 2775 ± 52 cal. yr BP was determined for the basal peat from Rawhitiroa. K-Ar dating performed previously indicated that these cones were about 0.30 my old. The pollen data indicated that a kauri-conifer-broadleaved forest was consistently present around Whangarei during the Holocene. At Maungatapere the arrival of Maori at c. 1360 AD was inferred from the marked decrease in Dacrydium cupressinum and the appearance of new species. This was an important horticultural site and was not repeatedly burned. At Rawhitiroa, the arrival of Maori possibly at c. 1200 AD was indicated by a decline in forest trees and the increased abundance of Pteridium esculentum and charcoal fragments. This occurred prior to the deposition of the Kaharoa Tephra, the presence of which was noted in the Rawhitiroa core. The Maungatapere wetland is currently a fertile swamp forest while the Rawhitiroa wetland is an infertile bog dominated by Sphagnum and sedges. The difference in the fertility of the two wetlands can be partially attributed to the activities of humans. Repeated forest fires at Rawhitiroa increased waterlogging and stimulated the growth of herbaceous wetland vegetation, causing the rapid build-up of peat and infertile conditions. The forest at Maungatapere was not repeatedly burned and the wetland became drier over time, maintaining its fertility. The incomplete core of peat infill at Maungatapere was a limitation of this project.Item A high resolution record of late quaternary climatic and environmental change in Taranaki, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Earth Science at Massey University, Palmerston North, New Zealand(Massey University, 2013) Tinkler, Robert JohnA high-resolution characterisation of climatic and environmental change in Taranaki, New Zealand over the last 80,000 years using biotic and abiotic proxies is presented. This research contributes to the small set of sediment cores that extend from the present back through the Last Glacial Maximum (LGM) in the southern North Island, and adds to the small number of near-continuous cores in New Zealand. Fossil pollen data presented here provides a record of vegetation changes in response to climate change (temperature, wind and rainfall). In addition, the project applies a recently developed pollen temperature transfer function (Wilmshurst et al. 2007) to quantify, for the first time, temperature change across the entire LGM in this region, and elucidates the timing of Late Quaternary New Zealand climatic events and phases. Climate change timing and magnitude is tested against the climate event stratigraphy (CES) developed by the NZ-INTIMATE (INTegration of Icecore, Marine and Terrestrial archives) group (Alloway et al. 2007), including: Last Glacial Coldest Period (LGCP); the mid-eLGM Interstadial; the Last Glacial-Interglacial Transition (LGIT); Termination I; the Antarctic Cold Reversal (ACR); the Late-Glacial Warm Period (LGWP), the Late-Glacial Reversal (LGR); and Early Holocene Warming (EHW). During the Moerangi Interstadial between 40,000 and 30,000 cal yrs BP, both the Eltham and coastal Taranaki pollen records show that cold-climate taxa such as Nothofagus menziesii, Nothofagus subg. Fuscospora, Hoheria, Plagianthus, Phyllocladus and Poaceae dominated the pollen assemblage. In addition to being cold, low numbers of fern and tree fern spores imply that conditions were drier than present. The LGCP at Eltham (29,000 – 18,000 cal yrs BP) began around 1,200 years earlier than similar records from elsewhere in New Zealand. Transfer functions suggest that mean annual temperatures at the LGCP/ LGM at Eltham were 5.7°C cooler than present. Within the LGCP, the mid-eLGM Interstadial described in similar records from New Zealand seems to be evident in the W-MAT-derived temperature curve at Eltham, where warming of around 0.8°C occurs between 27,000 and 24,500 cal yrs BP. The LGIT appears to have begun around 18,000 cal yrs BP and concluded around 14,600 cal yrs BP at Eltham, which agrees well with speleothem data from Northwest Nelson, but is more short-lived than at Otamangakau Bog where the LGIT is thought to have persisted for another 1,500 years. A period of sharp cooling inferred from the Eltham pollen record between 16,600 and 15,000 cal yrs BP, when mean annual temperature fell between 1°C and 4°C from the previous period, is matched in time, but not in intensity at some other western and central North Island, and some South island sites, and may be a sampling artefact. The LGWP duration at Eltham (14,600 – 13,500 cal yrs BP) broadly corresponds with NZ-INTIMATE and Northwest Nelson estimates of 14,800 – 13,500 cal yrs BP; mean annual temperatures at Eltham came within 0.6°C of modern-day mean annual temperatures at this time. The timing of the LGR at Eltham shows good agreement with NZ-INTIMATE estimates (Alloway et al. 2007; Lowe et al. 2008), that is, from around 13,500 to 12,500 cal yrs BP. The LGR onset at Eltham preceded onset at the Auckland maars by 600 years and concluded 1,500 years earlier than at Auckland; mean annual temperature at Eltham at this time was approximately 2°C cooler than the present day MAT of 11.2°C. The EHW event commenced at Eltham around 12,500 cal yrs BP, around 1,000 years earlier than at Kaipo Bog, Otamangakau Bog; and largely synchronous with the Auckland maars and Okarito. Pollen records from coastal Taranaki sites span d18O Stage 5a (Otamangakau Interstadial, c. 80,000 yrs BP) through to d18O Stage 2 (Last Glacial-Interglacial Transition, c. 18,500 cal yrs BP), and encompass the stadial complex between these two interstadials (d18O Stage 4, c. 70,000 – 60,000 yrs BP). These records contribute to the small number of pollen-based paleoenvironmental and paleoclimatic narratives for New Zealand extending from the LGIT to the Otamangakau Stadial (d18O stage 5a) time periods. A major contribution of the current A High Resolution Record of Late Quaternary Climatic and Environmental Change in Taranaki, New Zealand study is to reconstruct and characterise d18O stage 5a and d18O stage 4 temperatures based on two pollen transfer functions developed by Wilmshurst et al. (2007). During d18O Stage 5a around 80,000 cal yrs BP, conditions were warmer and wetter than the succeeding glacial. d18O Stage 4 and the early part of d18O Stage 3 were cool with relatively low precipitation and were likely to have been windy at coastal Taranaki sites. Although d18O Stage 4 was cool, it was not as cold as the LGM: pollen transfer functions showed decreases in estimated mean annual temperature from d18O stage 5a, with mean annual temperatures falling around 2°C to reach 7°C. Precipitation likely decreased during d18O stage 4, as indicated by low levels of drought-intolerant taxa Dacrydium cupressinum, Cyathea smithii, and monolete spores, whilst low shrub diversity implies that disturbance was likely to have been low. During early d18O stage 3, the climate warmed and became wetter in coastal Taranaki, as indicated by increasing conifer abundance; in particular Dacrydium cupressinum, high abundance of Cyathea smithii, and a decline in cold-tolerant Nothofagus, Halocarpus, Asteraceae, and Poaceae after 60,000 yrs BP. These conditions persisted for < 5,000 years before temperatures decreased again, then between 50,000 and 40,000 yrs BP the decline in Poaceae and cold-tolerant shrubs Phyllocladus, Halocarpus and Asteraceae, as well as the sharp rise in tall tree conifers, all point to climate amelioration. Conditions were still relatively cool; although pollen transfer functions imply that that mean annual temperatures increased slightly, with mean annual temperature estimates fluctuating between 7°C and 8°C, this was approximately 3 to 4°C cooler than present. For the first time in New Zealand, aerosolic quartz dust was extracted from organic sediments; this peat-derived data informs a paleowind narrative for Taranaki. The technique used in the current study to extract quartz from peats can be considered successful, insofar as relatively pure samples of quartz could be isolated in sufficient mass to be able to measure them, and relate the data to the age model and the coeval pollen influx. The paleowind reconstructions from Eltham can be summarised as follows: strong winds dominated between 36,200 and 35,100 cal yrs BP, 30,746 and 32,101 cal yrs BP, 28,364 to 17,477 cal yrs BP, and 16,118 to 15,806 cal yrs BP. Intermediate winds occurred between 30,746 and 28,364 cal yrs BP, 17,477 and 16,118 cal yrs BP, and 15,619 to 14,916 cal yrs BP; winds of light intensity dominated between 34,777 and 32,101 cal yrs BP and 14,916 and 9,900 cal yrs BP. Major dust peaks at 31,358 cal yrs BP; 21,300 cal yrs BP and 15,955 cal yrs BP all correlated well with the Vostok ice core as well as marine core P69 (Stewart & Neall 1984), and Onaero and Waitui in northern Taranaki. Similarly, dust minima after about 15,000 cal yrs BP at Eltham, Vostok, marine core P69, Onaero, and Waitui suggests that the quartz dust signature at Eltham is consistent with both global and regional estimates of dust influx as the atmospheric dust load responded to changes in wind direction and strength, in particular the intensity of westerly winds, and changes to sediment source area characteristics such as vegetation cover. Combining fossil pollen data and aerosolic quartz dust results is a new technique to investigate the relationship between wind intensity, temperature and plant assemblages. The Eltham fossil pollen and aerosolic quartz data was analysed to determine how the relative proportions of competitive, stress tolerant and ruderal taxa respond to winds of differing intensities over time, as well as quantifying the impact of wind of different intensities on plant diversity over the period 36,200 to 9,900 cal yrs BP. In essence, competitor, C-selected taxa increased in relative abundance, and stress-tolerant, S-selected and ruderal, r-selected taxa decreased over the last 15,000 years at Eltham, as both temperature and wind intensity ameliorated. Wind data was examined against pollen diversity data to test the Intermediate Disturbance Hypothesis (IDH) in the vegetation of the Taranaki region. A moderate relationship between floral diversity and dust flux was found, with periods of high and low dust flux corresponding to lower diversity, and periods of intermediate dust flux corresponding to higher diversity, as predicted by the IDH.Item A dynamical systems framework for modelling plant community organisation: a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University(Massey University, 1996) Cole, Anthony OwenThis thesis reports the results of ecological modelling research based on the use of absolute fossil pollen data as a proxy for actual measurements of historic vegetation change. The theme of this project is community organisation while the topic of special interest is community behaviour. The theory of community organisation includes some of the most fascinating and controversial problems in ecology. As defined in this thesis, community organisation is the study of the forces or mechanisms responsible for shaping the structure and behaviour of a community through time. An unresolved and persistent problem in community ecology has been the question of whether or not natural communities are capable of equilibrium behaviour. During the 1970s, key theoretical developments led community ecologists to question this traditional assumption. Today, the non-equilibrium paradigm is considered to be a more likely model for community organisation. The history of these major theoretical changes is reviewed in this thesis with the objective of deriving and testing hypotheses of plant community organisation. The hypothesis testing reported in this thesis is based on a new modelling paradigm. This framework required a flexibility that would permit its application to a wide range of ecological models and a sensitivity to the limitations of fossil pollen accumulation rate (PAR) data. Field data has been obtained from two plant communities: a Mangrove community located on the coastal plains of the Fijian island of Totoya and a lowland mixed beech forest, located within the ring plain of one of New Zealand's active volcanoes (Mt. Ruapehu). This combination of study sites permits the research hypotheses that are advanced in this thesis to be tested in plant communities of varying environmental, temporal, spatial and structural characteristics. The results of this research indicate that the plant communities studied exist in a low to intermediate density region, well below any theoretical region of density-dependency. The density vague behaviour of these communities appears to the result from stochastic domination. In conclusion, these results support the non-equilibrium model of community organisation. The implications of this research for palynologists involved in human impact studies and empirical modelling research are evaluated. Future objectives for theoretical modelling research in this area are suggested.Item Late holocene changes in the vegetation of Western Taranaki investigated by soil palynology : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University(Massey University, 1987) Lees, Cynthia MThe study area in western Taranaki is dominated by the andesitic volcano, Mount Egmont.Palynological study of 22 fossil pollen sites from a vide range of sediments has produced evidence of change in vegetation over last 4000 years.The resilience of the indigenous vegetation ensured survival of temperate lowland forests until the arrival of European settlers about 150 years ago.Within this period,deforestation of the lowlands has been almost complete.Surviving forest is protected within Egmont National Park. There is little evidence of pre-European deforestation,but indications of earlier fires are thought to be due to an increase in the Maori diet of Pteridium rhizomes,dictated by a change of climate about 400yr B.P. Information has been gained in general terms about the effects of older tephras and in detail about damage and recovery after tephras deposited within the last 400 years.A revised tephrochronology for the last 400 years is offered. Palynological evidence suggests that an equable climate existed between 4000-1400yr B.P. A decline of Ascarina from very high values at this time to low values at 400yr B.P. has been interpreted as due to a prevalence of droughts.Since 400yr B.P. the climate has been wetter and cooler.This, together with the availability of newly exposed sites due to volcanic activity,has resulted in a dominance of Weinmannia in the Mount Egmont forests. Such dominance is not seen in pollen profiles of older sites over the last 4000 years.Item Palynological evidence of vegetation dynamics in relatively undisturbed and disturbed sites in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand(Massey University, 2004) Li, XunNew Zealand forest has been affected by both natural and anthropogenic disturbances. Protecting and restoring indigenous forest is one of the focal issues in conservation of New Zealand, and understanding vegetation dynamics is a key part of management strategies. The longevity of most of New Zealand trees impedes short-term vegetation dynamic studies. Instead fossil pollen records provide one of the most valuable sources of long term data to trace vegetation development. In this study, pollen records are used as proxies of vegetation population to test the roles of long-term climate change and transient environmental disturbances in vegetation dynamics. Two sediment cores, from Sponge Swamp, Haast, and Tiniroto Lakes, Gisborne, were collected as representatives of undisturbed and disturbed sites, the former being used as a reference site to separate out the effects of climate and evaluate the impact of disturbance on the vegetation. Pollen data were inspected using Tilia, and zones defined. Principal component analysis (PCA) was performed on pollen data to summarise the change in species composition over time, and the sample scores of the first PCA axis were exploited as an index of vegetation dynamics for further comparison. Redundancy analysis (RDA) is also applied to help interpretation of the vegetation change with respect to environmental factors. The result of this study indicates that the vegetation development in both sites is characterized by non-equilibrium dynamics, in which vegetation composition is changing continually through time. In Sponge Swamp, this change is steady and consistent over the whole time span, with a consistent decline of Ascarina lucida and a progressive increase of cold tolerant or moisture-stressed taxa, like Gleichenia and Lycopodium australianum. Subsequently there is a partial replacement of swamp forest taxa such as Dacrycarps dacrydioides and tree ferns by Prumnopitys taxifolia, and further expansion of Nothofagus and Phyllocladus is distinguished. A climate gradient, from mild and wet to cooler and/or drier is suggested from the pollen evidence, and appears the driving force for the vegetation dynamics at that undisturbed site. At Tiniroto, however, the vegetation development is divided into two stages. Before c. 2300 yr BP, the vegetation change is steady and consistent which is comparable to that from Sponge Swamp. A forest invasion, a process of gradually replacing open land and light-adapted taxa, such as Dodonaea viscosa, Coprosma, Pseudopanax, Schefflera digitata, Pteridium, Hebe and members of the family Fabaceae and Asteraceae, by increasing proportions of forest taxa, characterise this change. Climate amelioration with increased rainfall is responsible. After c. 2300 yr BP, this trend was frequently punctuated by disturbances, in which sudden changes of vegetation occur, generating substantial fluctuations about the trend. From RDA, sample age explains more than 20% of the variance of species data at both sites. The long-term directional climate change derived from pollen evidence of Sponge Swamp and at least partly at the Tiniroto site, may be represented by the explanatory variable age. At Tiniroto, additional variance is also explained by the explanatory variables charcoal and pollen taxonomic richness, suggesting the impact of disturbance on vegetation dynamics. The impact of disturbance on vegetation dynamics becomes clearer after the climate gradient is removed. Autocorrelation analysis on detrended sample scores of the first PCA axis suggests further differences between the two sites, in response to local disturbances. There is little dependence of the present state of vegetation composition on its past state in the Sponge Swamp site; instead, the vegetation composition is affected by various "random" events, implying small disturbances such as floods, or landslides caused by earthquakes etc. At Tiniroto, the change of vegetation composition is more "successional", and the present state of vegetation depends only on the immediate past state, due to the impact of catastrophic disturbance. Despite the Tiniroto site having been subjected to a long history of disturbance, the climate gradient, which is distinct at the earlier stage, becomes less identifiable and partially masked by outbreaks of disturbances only since c. 2300 yr BP. This implies that the relative role of disturbance on vegetation dynamics with respect to climate is depended on different types or different levels of disturbances and different responses by the vegetation. Short-term vegetation responses to different types of disturbance were examined by fine resolution pollen analyses around five disturbance episodes, including the Taupo (1850±10 yr BP), Waimihia (3280±20 yr BP), Whakatane (4830±20 yr BP) eruptions, and two charcoal peaks (c. 1100 yr BP and c. 2300 yr BP). Almost no vegetation change occurred relative to the eruption within the Whakatane and Waimihia episodes, except that a temporary rise of shrubs and ferns corresponded with intermittent occurrence of charcoal particles. Substantial vegetation change relative to disturbance was found within both the Taupo episode and the fire episode around c. 2300 yr BP, in which establishment of ensuing semi-open vegetation was encouraged for decades. The fire c. 2300 yr BP transformed part of the forest into fernland, while the Taupo eruption turned part of the shrubs and tree ferns into bracken field. Although it is difficult to judge the effect of the fire around 1100 yr BP as the result was unreliable due to contamination, the vegetation at Tiniroto is suggested to be more vulnerable to fire than tephra. Non-equilibrium dynamics are common in New Zealand forests, even at stable sites such as Sponge Swamp, due to climate change. Locally these non-equilibrium dynamics appear highly responsive to disturbances, esp. at Tiniroto. Even disturbances at Tiniroto are dynamic and a change of disturbance regime is suggested around the later disturbance episodes. This change is possibly due to climate increasing the fire frequency, but an alternative explanation is the presence of humans earlier than currently accepted. Forests and forest ecological studies in New Zealand are very dynamic, and forest management needs to improve to incorporate these dynamics.Item An automated pollen recognition system : a thesis submitted to Massey University, Turitea, Palmerston North, New Zealand in fulfilment of the requirements for the degree of Master of Engineering(Massey University, 2006) Allen, GaryA system was developed with the aim of demonstrating that the tedious tasks of classifying and counting pollen on slides could be performed automatically to a standard comparable with that of human experts. Automation of pollen classification and counting will advance the science and range of applications of palynology. The system developed is a completely functioning prototype. After initial set up and training it is automatic in operation. System tests have demonstrated that the concept is viable and that the prototype developed is at a stage that it is of practical use to palynologists. There are opportunities for improvements and added functionality. Now that the system is developed and characterised, it provides a benchmark for gauging the efficacy of future improvements and adaptations. The system is presently adaptable to many different classification problems within palynology and would be adaptable for other automated microscopic classification or imaging tasks.Item Automatic Recognition of Light Microscope Pollen Images(Massey University, 2006) Allen, Gary; Hodgson, Bob; Marsland, Stephen; Arnold, Greg; Flemmer, Rory; Flenley, John; Fountain, DavidThis paper is a progress report on a project aimed at the realization of a low-cost, automatic, trainable system "AutoStage" for recognition and counting of pollen. Previous work on image feature selection and classification has been extended by design and integration of an XY stage to allow slides to be scanned, an auto focus system, and segmentation software. The results of a series of classification tests are reported, and verified by comparison with classification performance by expert palynologists. A number of technical issues are addressed, including pollen slide preparation and slide sampling protocols.